21538224 has 50 divisors (see below), whose sum is σ = 62341620. Its totient is φ = 7178976.

The previous prime is 21538219. The next prime is 21538261. The reversal of 21538224 is 42283512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 7014 + ... + 9605.

Almost surely, 2^21538224 is an apocalyptic number.

21538224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21538224 is an abundant number, since it is smaller than the sum of its proper divisors (40803396).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21538224 is a wasteful number, since it uses less digits than its factorization.

21538224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16639 (or 16624 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21538224 is about 4640.9292173012. The cubic root of 21538224 is about 278.2295776236.

The spelling of 21538224 in words is "twenty-one million, five hundred thirty-eight thousand, two hundred twenty-four".